Cool multimodal video in Google's top 100 List
Here's a fantastic multimodal demo on a table top display in which the user uses a combination of speech and two hand interactions to control Google Earth and Warcraft III. I've seen Bill Gates showing some tabletop interaction scenarios at a keynote (CES??) sometime in the recent past, but this blows it away in terms of being a compelling demo.
The demo is based on the research of Edward Tse, a CS Ph.D. student at the University of Calgary. There is similar work being done at MIT.
You can watch the demo at Google Video.